Structure Stability of External Mass Turnover Fields of the Djankuat Glacier

Abstract

The regularity and variability of accumulation, ablation, and mass balance distribution on the Djankuat Glacier were investigated to assess the spatio-temporal stability of its external mass turnover fields. A 2019/20–2023/24 time span, characterized by varying degrees of abnormality in the annual budget parameters, was selected as a case pentad for testing. Interannual differences in snow accumulation and melting patterns affect the spatial structure of the fields – obvious shifts of maxima and minima areas are noticed, inter alia. Nevertheless, persistent structural similarities across years indicate a certain degree of temporal and spatial stability. The present analysis employs the field similarity hypothesis originally developed by V.V. Popovnin (1989), which evaluates the variability of the functional relationship between gridded balance parameters and those averaged either over corresponding alti-morphological zones or over the entire glacier. For each grid node, variation coefficients of normalized values are calculated, followed by correlation analysis between the normalized node values and the corresponding zonal and glacier-wide averages. Concerned are both year-to-year correlations and the stability of annual fields relative to the long-term average pattern. Eventually the plots with the highest and lowest stability indices are identified within the glacier area. The alti-morphological zonation is found to align more consistently with the similarity hypothesis than glacier-wide averages. Among the three studied mass balance parameters, the ablation field demonstrates the greatest stability, whereas the accumulation field exhibits the highest variability. Correlations between annual and multi-year fields exceed those between two arbitrary years. Obtained results can be applied for indirect mass-balance plotting and calculations as well as for predicting accumulation, ablation and overall mass balance patterns.